JPH06279673A - Nonhalogenous flame-retardant polyamide molding material - Google Patents

Abstract

PURPOSE: To obtain a nonhalogen flame-retardant polyamide molding material which is excellent in electrical insulating properties and dimensional stability and is useful for parts of electrical home appliances by compounding a polyamide, a thermoplastic arom. polymer, magnesium hydroxide, and glass fibers in a specified wt. ratio.

CONSTITUTION: This material comprises 10-60 wt.% polyamide, 2-30 wt.% thermoplastic arom. polymer (e.g. poly-p-phenylene sulfide), 10-50 wt.% magnesium hydroxide, and 5-50 wt.% glass fibers, the sum of ingredients A to D being 100 wt.%.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

This invention relates to polyamides 10 to 60.
% By weight, thermoplastic aromatic polymer 2 to 30% by weight, magnesium hydroxide 10 to 50 as a flame retardancy-imparting component
It relates to a halogen-free, flame-resistant thermoplastic polyamide molding composition which comprises 10% by weight and 10 to 50% by weight of glass fibers.

[0002]

BACKGROUND OF THE INVENTION Large quantities of polyamides, especially glass fiber reinforced polyamides, have been successfully used as molding materials, for example in mechanical assembly, electrical engineering, and domestic appliance engineering. For application to these combustion tests such as UL94
(Underwriter Laboratories
There is often a need to make polyamides flame resistant in order to withstand the industrial requirements of tests according to USA). Various flame retardants are used for this purpose. However, each of them has certain drawbacks. The known flame retardant is red phosphorus,
It consists of organic halogen compounds or melamine salts.

Red phosphorus is mainly glass fiber reinforced polyamide 6
6 (see for example DE 37 13 746 and EP 299 444). Due to the inherent reddish brown color of phosphorus, the polyamides treated with it can only be supplied in a dark color.
Furthermore, they tend to form phosphines and phosphates under the influence of heat and moisture. Phosphine is toxicologically questionable and corrodes copper-containing contact devices in electrical equipment. The corroded film thus formed has electrical insulating properties, and therefore generates heat when energized, resulting in dielectric breakdown of electrical equipment in extreme cases. The following organohalogen compounds have been used as flame retardants for polyamides: brominated biphenyls and biphenyl ethers in combination with antimony trioxide, chlorinated cycloaliphatic hydrocarbons, brominated styrene oligomers, brominated aromatic nuclei. Polystyrene zinc salt with or iron oxide is further used as synergist.

Most halogen-based flame retardants begin to decompose at the processing temperatures of conventional polyamides. During this decomposition, food gas is generated, which destroys the electrical contacts of appliances and devices.

Melamine salts have just become clear to be useful as flame retardants for unreinforced polyamides. Polyamides treated with these have a light intrinsic color and good electrical properties. However, the relatively low decomposition temperature of melamine salts is a drawback.

Another flame retardant used in polyamides is magnesium hydroxide. The use of magnesium hydroxide as a flame retardant for thermoplastics has long been known (P
plastics and Rubber Procedures
sing Applications 6 (198
6) 169-175). In order for the thermoplastic to be flame resistant, ie Class according to eg UL94
The concentration of magnesium hydroxide used to withstand the V0 flammability test depends on the inherent flame resistance of the thermoplastic involved. If it is very low, like polyolefins, a high concentration of magnesium hydroxide is needed.
For example, for polyolefins, the required amount is at least 60% by weight, while for EPDM rubber the required concentration is at least 70% by weight. Aliphatic polyamides and copolyamides such as polyamides 6,66, 610, 11 or 12 also have very low intrinsic flame resistance. Thus, so far, very high concentrations of magnesium hydroxide are required to make them flame resistant as well. For example, at least 55% by weight was required for polyamide 6.

However, the need for such high concentrations of magnesium hydroxide means that some drawbacks must be accepted.

Thus, the mixing of magnesium hydroxide is usually carried out by adding the measured amount of magnesium hydroxide to the polyamide melt in the twin-screw extruder, but it becomes more difficult as the required concentration of magnesium hydroxide increases. Moreover, mixing becomes uneconomical as the concentration of magnesium hydroxide increases. This is because satisfactory diffusion of concentrated magnesium hydroxide in the polyamide melt is possible only when low extrusion rates are used. Among other factors, this is related to the fact that the magnesium hydroxide particles do not wet well with the polyamide melt. For this reason, a large amount of unsaturated metal soap is added to the compounding batch (Japanese Patent Laid-Open No. 53-12943), or magnesium hydroxide coated with an alkali metal salt of oleic acid is used (European Patent No. 52868). , Or maleated polyolefins whose further function is imparted by maleic anhydride are added to the batch (EP 335165). However, both of these measures deteriorated the industrial properties of polyamide.

In addition, when a high concentration of magnesium hydroxide is mixed with a fibrous reinforcing material such as glass fiber during the production of the polyamide-magnesium hydroxide composite, the mechanical properties of the composite are improved and the dimensional stability under heat is improved. Limit the possibilities.

[0010]

For these reasons, the basic object of the present invention was to develop a halogen-free, flame-resistant molding material consisting of polyamide and magnesium hydroxide in the lowest possible concentration.

[0011]

This object has been achieved by incorporating in polyamide a magnesium hydroxide and optionally glass fibers as well as a thermoplastic aromatic polymer.

Accordingly, the present invention provides a halogen-free, flame-resistant thermoplastic molding material comprising: A) 10 to 60% by weight of polyamide, preferably 20 to 45% by weight, and B) 2 to 30% by weight of thermoplastic aromatic polymer. , Preferably 5 to 25% by weight, C) 10 to 50% by weight of magnesium hydroxide, preferably 20 to 40% by weight and D) 5 to 50% by weight of glass fiber, preferably 10 to 30% by weight and components A to D Refers to materials comprising 100% by weight.

The molding compositions according to the invention are flame-resistant without the disadvantages of the red phosphorus- or halogen-containing flame retardants mentioned above.

The polyamide of the molding material according to the invention comprises a partially crystalline polyamide and an amorphous polyamide, a diamine and a dicarboxylic acid and / or at least 5
It is prepared by a known polycondensation method starting from a membered lactam or the corresponding amino acid. Suitable starting materials are aliphatic and aromatic such as adipic acid, 2,2,4- and 2,4,4-trimethyladipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, isophthalic acid, terephthalic acid. Group dicarboxylic acids, hexamethylenediamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine, diamino-dicyclohexylmethane isomers and diamino-dicyclohexylpropane isomers, isophoronediamine, xylenediamine isomers, bis Aliphatic and aromatic diamines such as aminomethylcyclohexane and aminocaproic acid,
It consists of aminoundecanoic acid, aminolauric acid, or the corresponding aminocarboxylic acids such as lactams. Also included are copolyamides formed from a plurality of the above monomers.

Thermoplastic aromatic polymers within the meaning of the invention consist, for example, of poly-p-phenylene sulfides, polyarylene ethers, aromatic polysulfones and aromatic polyetherimides. This type of thermoplastic aromatic polymer is commercially available under the following trade names: For example, polyphenylene sulfide: Ryton ™, F
ortron ™ (Philips Petrol)
eum / Hoechst) Polyarylene ether: PPO and PPE (GE and BASF) Polysulfone: Ultrason ™
S and Ultrason ™ E (BASF) Polyetherimide: Ultem ™ (G
E) Aromatic Polyamide: Amodel ™
Both (AMOCO) and Ultramid 6T (BASF) magnesium hydroxide are suitable for the flame-resistant molding material according to the invention. However, flake-like particles, magnesium hydroxide having a specific surface area of 10 over 12 m ² / g are particularly preferred. Finally, the magnesium hydroxide may be pretreated to improve its bond with the polyamide / polyarylene sulfide matrix.

Suitable types of magnesium hydroxide are commercially available, for example from Martinswerk of Bergheim.
Magnifin H 10 manufactured by Tokyo, Kis manufactured by Tokyo Kyowa
umaE5 or Leoven's Veitsche
It is available under trade names such as Ankermag from Nagnesitwerke.

The molding composition according to the invention may contain additional fibrous reinforcing materials and / or inorganic fillers. Besides glass fibers, suitable reinforcing materials consist of carbon fibers, aramid fibers, inorganic fibers and whiskers. Suitable inorganic fillers consist, for example, of calcium carbonate, dolomite, calcium sulfate, mica, talc and kaolin. The fibrous reinforcing material and the inorganic filler may be surface treated to improve their mechanical properties.

Furthermore, the flame-resistant molding materials according to the invention may contain other additives in order to improve their engineering properties. Additives of this type consist of pigments, heat and weathering stabilizers, release agents, flow promoters.

The flame-resistant molding composition according to the invention generally comprises first melting a mixture of polyamide and polyarylene sulfide in an extruder or a kneader and then a certain amount of magnesium hydroxide, optionally glass fibers and optionally other reinforcing materials. And fillers and / or further additives are added to these melts which are evenly dispersed using shear forces.

Processing of the flame-resistant molding material according to the present invention into a molded product is usually carried out by injection molding, and the molded product is processed into a part by extrusion.

The invention relates to the use of the molding compositions according to the invention for the production of moldings and the moldings produced from the molding compositions according to the invention.

[0022]

EXAMPLES The following examples show that the flame resistance of molding compounds composed of polyamide 6, glass fibers and magnesium hydroxide is decisively improved by poly-p-phenylene sulfide, and that poly-p-phenylene sulfide is used, for example. Thus, it is possible to obtain a flame-resistant molding material even if the concentration of magnesium hydroxide is low.

The following starting materials were used in the examples: Polyamide 6: Durethane ™ B
31F (Bayer AG; relative viscosity 3 Pa.s 1%
m-cresol solution) -poly-p-phenylene sulfide: chain polyphenylene sulfide, relative viscosity ε _rel = 65 Pa.s. s
(1000s ^-1 ) -Glass fiber: Bayer Glas 7919, average diameter 11 μm; average length 4.5 mm-Magnesium hydroxide: Magnifin H 10
(Martinswerk), heating loss (1100 ° C)
40%.

The molding material used in the examples is a twin-screw extruder (ZS manufactured by Werner and Pfleiderer) which is a mixture of polyamide 6 and poly-p-phenylene sulfide.
K32) melted and then made by adding a certain amount of glass fiber and magnesium hydroxide to the melt. A length of circular extruded rod was extruded from the molding material made in this way; the extruded rod was then granulated. 1.6m
m thick ASTM specimens were injection molded from granular material at a melting temperature of about 300 ° C. The flammability test according to UL94 was performed using this test piece.

The composition of the molding material used in the examples and the result of the combustion test are shown in the following table.

[0026]

[Table 1]

Nw = does not endure combustion test C * = comparative example The main features and aspects of the present invention are as follows.

1. Comprising A) 10 to 60% by weight of polyamide, B) 2 to 30% by weight of thermoplastic aromatic polymer, C) 10 to 50% by weight of magnesium hydroxide and D) 5 to 50% by weight of glass fiber, wherein A halogen-free, flame-resistant polyamide molding material in which the total of components A to D is 100% by weight.

2. A) 20 to 45% by weight of polyamide, B) 5 to 25% by weight of thermoplastic aromatic polymer, C) 20 to 40% by weight of magnesium hydroxide, and D) 10 to 30% by weight of glass fiber. 1. The molding material according to 1 above.

3. 2. The molding material as described in 1 above, wherein the thermoplastic aromatic polymer is polyarylene refined, polyarylene ether, polysulfone, polyetherimide or aromatic polyamide.

4. 3. The molding material as described in 3 above, wherein the thermoplastic aromatic polymer is poly-p-phenylene sulfide.

5. The molding material according to any one of the above 1 to 4, wherein the polyamide is a partially crystalline aliphatic homopolyamide or copolyamide.

6. Characterized in that they additionally contain other fibrous reinforcing materials, but the sum of their concentrations and of the C) and optionally D) components is not more than 80% by weight, based on the total amount of molding compound. The molding material described in 1 to 5 above.

7. 1 above, characterized in that they additionally contain other inorganic fillers, but their concentration and the sum of the concentrations of C) and optionally D) are below 80% by weight, based on the total amount of molding compound. To 6 molding materials.

8. Use of the molding material according to any one of 1 to 7 as a molded body.

9. A molded body produced from the molding material according to any one of 1 to 7 above.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI technical display location C08L 71:12 81:06 79:08) (31) Priority claim number P43236766.6 (32) Priority Date July 15, 1993 (33) Priority country Germany (DE) (72) Inventor Aziz El Saed Germany 51375 Lef Erkusen Saar Lauterner Siyutraße 39

Claims (3)

[Claims] 1. A) 10 to 60% by weight of polyamide, B) 2 to 30% by weight of thermoplastic aromatic polymer, C) 10 to 50% by weight of magnesium hydroxide, and D) 5 to 50% by weight of glass fiber. Wherein the total of components A to D is 100% by weight, a halogen-free, flame-resistant polyamide molding material. 2. Use of the molding material according to claim 1 for producing a molded body. 3. A molded body produced from the molding material according to claim 1.